Multipolar medical electrical leads have been developed for delivering cardiac pacing therapies. Having multiple electrodes along a given heart chamber enables a clinician to select which of the electrodes to use for delivering pacing. Pacing site selection can be critical to achieving a positive clinical benefit from a pacing therapy, such as cardiac resynchronization therapy (CRT). Another consideration taken into account when selecting an electrode for delivering a cardiac pacing therapy is whether or not inadvertent activation of non-cardiac excitable tissue occurs in response to a cardiac pacing pulse. Stimulation of the right or left phrenic nerve may occur when cardiac pacing electrodes are positioned along the right heart chambers or the left heart chambers, respectively in the vicinity of the right or left branch of the phrenic nerve. For example, a quadrapolar lead extending along the left ventricle in a cardiac vein may position one or more electrodes in close enough proximity to the left phrenic nerve that cardiac pacing pulses delivered using the electrodes results in phrenic nerve stimulation (PNS) and diaphragmatic activation.
Testing multiple electrodes in various vector combinations for both cardiac response and other factors such as undesired PNS and hemodynamic response can be a time-consuming task for a clinician and poses a burden on the patient undergoing repeated testing of different vectors while the clinician evaluates various responses. For example, when a left ventricular quadrapolar lead is implanted in a patient, the clinician may test up to sixteen bipolar electrode combinations for pacing capture threshold, hemodynamic response, PNS and other outcomes when selecting which pacing vector should be used for chronic therapy delivery.